JPS599892B2 - How to obtain a radiograph - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of obtaining a radiograph using a silver halide photographic material and to improvements in the photographic material for this purpose.

More particularly, the present invention relates to a method for obtaining a radiographic image by exposing a silver halide photographic material to ionizing radiation by contacting it with a radiation fluorescent intensifying screen and then subjecting it to photographic processing, and the silver halide used therein. It relates to photographic materials. X-ray recording materials usually include silver halide photographic film and intensifying screens to increase the recording sensitivity to X-rays.
een) or a fluorescent plate are often used.

Exposure to excessive amounts of X-rays has harmful effects on the human body,
In order to obtain X-ray photographs with as little X-ray dose as possible, efforts are being made to increase recording sensitivity to X-rays. for example,
In addition to increasing the sensitivity of silver halide photographic emulsions, X-ray image intensifiers (X-ray image intensifiers)
system using a solid-state X-ray image intensifier (SOl
A system using the ld-Statelightamplifier has been developed. However, in either case, the image is ultimately recorded on the gelatin/silver halide photosensitive material as a fluorescent image. Traditionally, phosphors used for this purpose have been strontium-activated barium sulfate, lead-activated barium sulfate, silver-activated barium sulfate, and lead-activated barium sulfate. Calcium tungstate [CaWO,]
Zinc sulfide activated by silver, barium phosphate [Ba, (PO4) activated by eurobium]
, ] is a blue phosphor.

Particularly for medical purposes, radiographic...fluorescent intensifying screens used with silver halide materials have conventionally mostly contained barium sulfate activated by the calcium tungstate or lead as the phosphor. It was hot. Recently, as opportunities for medical X-ray imaging have increased, research has been carried out on fluorescent intensifying screens with high luminous energy intensity. In particular, the rare earth oxysulfide and oxyhalide phosphors activated by the other four rare earth elements have a high luminous energy intensity, which has been demonstrated by Lockheed Aircraft Co., Ltd.
craftCOrp. ) is known for his research reports. On the other hand, it is desirable that the X-ray photosensitive materials used, i.e., direct X-ray photographic materials and indirect X-ray photographic materials, be easy to handle, including development and fixing processes.

In particular, it is desirable to handle the product in a room that is as bright as possible.
This type of X-ray photographic material is manufactured by Fuji Photo Film Co., Ltd., for example. Handled under safe light using a /167 filter. The spectral transmittance curve of Fuji Photo Film's 7-filter filter is shown in FIG.

In other words, silver halide photosensitive materials for radiography are highly sensitive to the green fluorescence emitted from the above-mentioned improved phosphor upon radiation excitation, but have low sensitivity to safe light illumination. Sensitivity is desirable. Recently, the development and fixing steps for photosensitive materials using silver halide photographic emulsions have been increasingly shortened to 60 seconds to 120 seconds.

In such photographic processing, the sensitizing dye contained in the photographic emulsion is difficult to be washed out of the light-sensitive material, and therefore the processed photograph is likely to be contaminated (referred to as residual color) by the remaining dye. Merocyanine dyes, hemicyanine dyes, and trinuclear cyanine dyes are also often used for spectral sensitization in the green wavelength range. However, the spectral sensitization using these dyes has too wide a spectral sensitivity distribution and is therefore unsuitable for the purpose of sensitizing to a narrow specific wavelength range. Also, it is difficult to obtain high sensitivity.
In particular, it is disadvantageous for the spectral sensitization of highly sensitive silver iodobromide photographic emulsions because of its low sensitization rate. Furthermore, supersensitizers for these sensitizing dyes are difficult to find. For this type of purpose, the application of J monoaggregated cyanine dyes is advantageous and many are known. For example, techniques using imidazolocarbonanine dyes: US Pat. Nos. 2701198, 2945763, 2
No. 973264, No. 3173791, No. 3364031, No. 3397060, No. 3506443, Special Publication No. 43-4
No. 936 Yamata German Patent Application (0LS) 194475
No. 1, No. 2011879, No. 2018687, 2030
No. 326, and a technique using imidaoxacarbocyanine dye: Japanese Patent Publication No. 14030/1984.

Also, technology using pseudocyanine dyes: German patent application (0LS) No. 1936262, French patent No. 148805
No. 7 is also known. Some of these known cyanine dyes provide high spectral sensitivity, but their sensitizing wavelengths are too long and do not match well with the emission spectra of green phosphors, which have high luminescence sensitivity. There was a lot of residual color on the light-sensitive material, and I was not satisfied with it.

The object of the present invention is to achieve a method for obtaining radiographs with high sensitivity, ie, with a lower radiation dose, by a combination of a radiation intensifying screen and a photographic material. Another object of the present invention is to obtain radiographs with little residual color and high maximum image density in a method of obtaining radiographs by combining a radiation fluorescent intensifying screen and a photographic light-sensitive material.

A further object of the present invention is to provide a radiation phosphor intensifying screen with a maximum emission in the green region of the spectrum, which has high sensitivity to emission and can be handled with high safety under safe light;
It is an object of the present invention to provide a silver halide photographic material that has little residual color after photographic processing.

Still another object of the present invention is to obtain a silver halide photographic material with high sensitivity to green light, which is suitable for a rapid development process.

The present inventors have discovered that the combination of specific sensitizing dyes shown below effectively achieves the above objects of the present invention.

That is, the present invention combines at least one sensitizing dye represented by the following general formula (I) and at least one sensitizing dye represented by the general formula () to produce a silver halide photograph. This was achieved by incorporating it into an emulsion. In general formula (I), R.

is an alkyl group (including substituted alkyl groups)
For example, methyl group, ethyl group, n-propyl group, hydroxyethyl group, acetoxymethyl group, ethoxyethyl group, etc. R1 and R2 each represent an alkyl group (including substituted alkyl groups). For example, an unsubstituted alkyl group (such as a methyl group,
ethyl group, butyl group, etc.), hydroxyalkyl group (e.g., 2-hydroxyethyl group, 4-hydroxybutyl group, etc.), acetoxyalkyl group (e.g., 2-acetoxyethyl group, 3-acetoxypropyl group, etc.), and carboxy radical. Alkyl groups (e.g. 2-carboxyethyl group, 3-carboxypropyl group, 2-(2
-carboxyethoxy)ethyl group, etc.), alkyl groups with sulfo radicals (e.g. 2-sulfoethyl group, 3-sulfoethyl group, etc.),
-Sulfopropyl group, 3-sulfobutyl group, 4-sulfobutyl group, 2-hydroxy-3-sulfopropyl group, 2
-(3-sulfopropoxy)ethyl group, 2-acetoxy-3-sulfopropyl group, 3-methoxy-2
-(3-sulfopropoxy)propyl group, 2[2
-(3-sulfopropoxy)ethoxy]ethyl group,
2-hydroxy-3-(3'-sulfopropoxy)propyl group, etc.), aralkyl group (eg, benzyl group, phenylethyl group, etc.). However, at least one of R1 and R2 is an alkyl group having a sulfo radical. X represents an anion commonly used in cyanine dyes (eg, chloride ion, bromide ion, iodide ion, thiocyanate ion, p-toluenesulfonate ion, ethyl sulfate ion, etc.). m represents l. General formula () where z is a benzoxazole nucleus such as benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole, 5-bromobenzoxazole, 5-
Fluorobenzoxazole, 5-phenylbenzoxazole, 5-methoxybenzoxazole, 5-trifluoromethylbenzoxazole, 5-hydroxybenzoxazole, 5-carboxybenzoxazole, 6-methylbenzoxazole, 6-chlorobenzoxazole, 6 -methoxybenzoxazole, 6-hydroxybenzoxazole, 5,6-dimethylbenzoxazole, . Represents 4,6-dimethylbenzoxazole, 5-ethoxybenzoxazole, etc.

R is an alkyl group or a substituted alkyl group having the same meaning as R1 and R2, Q is a 2-thioimidazolidine-2,4-dione nucleus, for example, a 2-thioimidazolidine-2,4-dione nucleus,
3-ethyl-2-thioimidazolidine-2,4-dione nucleus, 3-(4-sulfobutyl)-2-thioimidazolidine-2,4-dione nucleus, 3-(2-carboxyethyl)
-2-thioimidazolidine-2,4-dione nucleus, 3-phenyl-2-thioimidazolidine-2,4-dione nucleus,
3-α-naphthyl-2-thioimidazolidine-2,4-
Dione nucleus, 1,3-diethyl-2-thioimidazolidine-2,4-dione nucleus, 1-ethyl-3-phenyl-2-
Thioimidazolidine-2,4-dione nucleus, 1,3-diphenyl-2-thioimidazolidine-2,4-dione nucleus,
1-(2-carboxyethyl)-3-phenyl-2-thioimidazolidine-2,4-dione nucleus, 1-phenyl-3-ethyl-2-thioimidazolidine-2,4-dione nucleus, 1-( 2-hydroxyethyl)-3-phenyl-2
-thioimidazolidine-2,4-dione nucleus, 1-(3-
(hydroxypropyl)-3-phenyl-2-thioimi
5 Dazolidine-2,4-dione nucleus, 1-(2-carboxyethyl)-3-(p-chlorophenyl)-2-thioimidazolidine-2,4-dione nucleus, 1-ethyl-3-n
-Butyl-2-thioimidazolidine-2,4-dione nucleus, etc. The phosphor used in the green-emitting fluorescent screen used in the present invention preferably has an atomic number of 39 or 5.
7 to 71 elements, such as yttrium, gadolinium, lanthanum, and cerium.

Particularly useful are other rare earth activated rare earth oxysulfide and oxyhalide fluorophores such as lanthanum or gadolinium oxybromides and oxychlorides activated with terbium or dysprosium, terbium, europium or europium. It is an oxysulfide of lanthanum or gadolinium activated with a mixture of samarium. Such rare earth fluorescent materials are disclosed in German patent No. 1282819, French patent No. 1540341, 1580544, 202
No. 1397, additional patent No. 94579 to French Patent No. 1473531, U.S. Patent No. 3546128, 34
18246, 3418247, 3705858, 3725704, 3778615 and IEEE in San Francisco, October 29-31, 1969.
A report titled "Rare Earth Oxysulfide February issue, No. 81-83
It is written on the page.

Such new rare earth fluorophores, especially gadolinium and lanthanum oxysulfides and oxyhalides activated with other rare earths such as erbium, terbium and/or dysprosium, have a high degree of X-ray stopping or average absorption power. It has a large emission intensity, allowing radiation workers to use substantially lower X-ray doses. A low amount of silver halide per unit area of a light-sensitive material is not only economically advantageous, but also generally advantageous in shortening processing time, particularly fixing time.

However, when a photographic light-sensitive material containing a small amount of silver halide per unit area is used, the maximum density and contrast of the obtained image are reduced. Although high maximum densities can be obtained using fine grain emulsions, their photographic sensitivity is low and large amounts of radiation exposure are required. Therefore, a photographic emulsion layer is desired which can provide sufficient maximum density and contrast even with a small amount of silver halide per unit area and has high sensitivity. According to the present invention, these requirements are met, and favorable results can be obtained even when the amount of silver per square decimeter of light-sensitive material is less than about 8611If. The features of the present invention are a benzimidazolooxacarbocyanine dye consisting of a benzoxazole nucleus substituted with 5-position "phenyl" represented by the general formula (1) and a 2-thioimidazolidine-2,4-dione represented by the general formula (). By spectrally sensitizing low-silver silver halide photographic emulsions using a combination with a dimethine merocyanine dye consisting of a core, the maximum density of the low-silver emulsion is not reduced, and the dye can be easily sensitized by a fluorescent intensifying screen. High sensitivity to light emission can be obtained.

Among the sensitizing dyes represented by general formula (1), R1 and R2
Particularly high sensitivity can be obtained when both are alkyl groups having sulfo radicals. The combination of a benzimidazolooxacarbocyanine dye consisting of a benzoxazole nucleus substituted with methoxy at the 5-position and a merocyanine dye represented by the chemical structural formula below is disclosed in the U.S. Defensive Publication.
PublcatlOn) T9O4O26.

Merocyanine dye for comparison (1) (corresponds to dye F of UST9O4O26) Merocyanine dye for comparison (2) (corresponds to dye E of UST9O4O26) Represented by the general formula () used in the present invention, Z) 5th position "phenyl" The combination of a benzimidazolooxacarbocyanine having a substituted benzoxazole nucleus and a dimethine merocyanine dye having a 2-thioimidazolidine-2,4-dione nucleus represented by the general formula () will be described later in Example (1st
As shown in Table 1), the combination described in UST9O4O26 provides high sensitivity.

In the method of the present invention, one or two of terbium-activated gadolinium oxysulfide, terbium-activated yttrium oxysulfide, and terbium-activated lanthanum oxysulfide are used in the fluorescent intensifying screen. Particularly high radiation sensitivity can be obtained when the above mixture is used as a phosphor.

Another feature of the invention is that by using the sensitizing dye combinations of the invention, processed photographic elements have less residual color due to the sensitizing dyes.

Among the dyes represented by the general formula () used in the present invention, both R1 and R2 are an alkyl group having a sulfo radical, and among dyes represented by the general formula (), R3 is an alkyl group having a sulfo radical. The combination with dyes with gives very little residual color. Another feature of the invention is that by using the combination of sensitizing dyes of the invention,
A complete optical filter (usually used for X-ray photographic materials)
For example, sufficient safety against safelight light using Fuji Film's FL7 filter can be obtained.

The combination of dyes known from UST9O4O26 has poor safelight safety, as shown in Examples (Table 2) below. Another feature of the invention is that the 0.000.
Sufficiently high spectral sensitization can be obtained even in a large-grain silver halide emulsion with an average grain size exceeding 7 μm.

Even dyes that exhibit excellent spectral sensitization for silver halide emulsions with relatively small grain sizes often exhibit poor spectral sensitization for emulsions with large grain sizes (for example, mesoalkyl-substituted thia carbocyanin). The combination of the dye of general formula (1) and the dye of general formula () used in the present invention is suitable for use in silver halide emulsions with an average grain size of over 0.7μ, particularly in high-sensitivity emulsions with an average grain size of over 1.2μ. Provides excellent green spectral sensitization to silver halide emulsions. Typical examples of the benzimidazolo-oxacarbocyanine dye represented by the general formula (1) used in the present invention are listed below.

However, the sensitizing dye used in the present invention is not limited to this.
2-thio- represented by the general formula () used in the present invention
Typical examples of dimethine merocyanine dyes containing a 2,4-imidazolidinedione nucleus are listed below, but the sensitizing dyes used in the present invention are not limited thereto.

The dye represented by the general formula (1) is
Those skilled in the art can easily synthesize the sensitizing dyes described in No. 30, JP-A No. 47-33626, etc. by referring to the above specifications, and those not described can be synthesized by similar methods.

The dye represented by the general formula () is disclosed in U.S. Patent No. 251900.
No. 1 No. 3822136, British Patent No. 1315773,
JP-A No. 48-33817 or F.M. Hemaichi (H
``The Cvanine Dyesand'' by Amer)
RelatedCompOunds”Intersci
eneePubllshers,. NewYOxlc(
1964) from page 511 onwards, those skilled in the art can easily synthesize the compounds, and those not specifically described can also be synthesized by similar methods.

Although various concentrations of individual sensitizing dyes can be used in the present invention, about 1.0% of sensitizing dye per mole of silver halide.
Advantageously, from 0.times.10@-5 to about 1.0.times.10@-3 moles are used.

In particular, about 4 x 10-5 to 1.6 x per mole of silver halide
Advantageously, 10@-4 moles of sensitizing dye are used. The usage ratio in the combination of dyes (molar ratio of dye represented by general formula (1)/dye represented by general formula ()) is preferably about 10/1 to about 1/10, especially about 5/1 to about 1/5 is the most effective.

The optimal concentration of sensitizing dye is determined according to methods known to those skilled in the art.
The sensitivity can be determined by dividing the same emulsion, allowing each part to contain a different concentration of sensitizing dye, and measuring the sensitivity.

The sensitizing dye is added to the emulsion by methods well known in this field.

These sensitizing dyes can also be directly dispersed in emulsions,
or first dissolved in a water-miscible solvent such as pyridine, methyl alcohol, ethyl alcohol, methyl cellosolve, acetone, etc. (or a mixture of such solvents) and diluted with water; These can be added to the emulsion in the form of a solution.

Moreover, ultrasonic vibration can also be used for this melting. Others, such as Special Publication No. 45-8231, Special Publication No. 44-23
No. 389, Special Publication No. 1977-27555, Special Publication No. 1977-2
No. 2948, German patent application (0LS) 194793
No. 5, U.S. Patent No. 3,485,634, U.S. Patent No. 33,426
Methods described in No. 05, US Pat. No. 2,912,343, etc. can also be used.

If desired, the sensitizing dyes can be dissolved separately in appropriate solvents and added to the emulsion separately, or each dye can be dissolved in the same or different solvents and added to the silver halide emulsion. It is also possible to use a method of mixing these solutions prior to.

The emulsion containing the sensitizing dye is applied to a suitable support such as gaff, cellulose derivative film, polyvinyl resin film (e.g. polystyrene film, polyvinyl chloride film, etc.), polyester film, synthetic paper,
Prior to coating on baryta paper, polyolefin-coated photographic paper, etc., the dye must be uniformly dispersed throughout the emulsion. These sensitizing dyes may be added to the emulsion at any time during the emulsion manufacturing process, but it is more convenient to add them after the second ripening is completed. The silver halide used in the present invention may be any one of silver chloride, silver bromide, silver iodide, silver chlorobromide, silver iodobromide, silver chloroiodobromide, etc.; Silver chlorobromide is preferred, and silver iodobromide with a silver iodide content not exceeding 3 mol % is particularly preferred.

These five silver halide grains are formed by a known method such as a single dinit method, a double dinit method, or an endroll double dinit method. Furthermore, even if the crystal structure of silver halide grains is uniform up to the inside, there is also a difference between the inside (COre) and the heterogeneous shell (Shell).
) with a layered structure, and British patent 6358
It may be of a so-called conversion type as described in No. 41 and US Pat. No. 3,622,318. Further, either a type in which a latent image is formed mainly on the surface or an internal latent image type in which a latent image is formed inside the particle may be used. These photographic emulsions are based on 6 The Theory of Photographic Processes.
aphicPrOces8, 1 Written by Mees, published by MacMillan, PhOtOgraphicC
hemistry)" Grafukide
s), Founkgin Press
It can be prepared by various methods such as an ammonia method, a neutral method, an acid method, etc. which are well known to those skilled in the art. After forming such silver halide grains, they are washed with water to remove by-product water-soluble salts (for example, potassium nitrate when silver bromide is made using silver nitrate and potassium bromide) from the system, and then Heat treatment can be performed in the presence of a chemical sensitizer to increase sensitivity without coarsening the particles. Also, without removing by-product water-soluble salts,
Sometimes it is used as is. These usages are described in the above book. The average diameter of the silver halide grains used (measured by, for example, the projected area method or number average) is preferably about 0.7 to 2.0 μm, particularly about 1.0 μm.
The effect of the present invention is large in the case of μ to 2.0 μ.

The silver halide photographic emulsion used can be processed by commonly used chemical sensitization methods, such as gold sensitization (US Pat. No. 254,008).
No. 5, No. 2597876, No. 2597915, 2399
No. 083, etc.); sensitization with group metal ions, sulfur sensitization (US Pat. No. 1,574,944, US Pat. No. 2,278,947, US Pat. No. 2,440,206, US Pat. No. 2,410,689, US Pat. No. 3,1894)
No. 58, US Pat. No. 3,415,649, etc.); cyclic sensitization (US Pat. No. 2,518,698, US Pat.
No. 610, etc.); or various sensitization methods combined therewith can be applied.

More specific chemical sensitizers include sodium thiosulfate and allylthiOcarbamide.
amide), thiourea, cystine and other sulfur sensitizers,
Noble metal sensitizers such as potassium chloroaurate, gold(4) thiosulfate, and potassium chloropalladate; ring element sensitizers such as stannous chloride, phenylhydrazine, and reductone; and the like may be included.
Polyoxyethylene derivatives (British Patent No. 981470, Japanese Patent Publication No. 31-6475, U.S. Patent No. 2)
No. 716062), polyoxypropylene derivatives,
Sensitizers such as derivatives with quaternary ammonium groups may also be included.

The silver halide emulsion layer of the light-sensitive material may contain a suitable antifoggant or stabilizer.

In addition, thiazolium salts described in US Pat. No. 2,131,038 and US Pat. No. 2,694,716; azaindenes (Az
aindenes); urazoles as described in US Pat. No. 3,287,135; sulfocatechols as described in US Pat. No. 3,236,652; oximes as described in British Patent No. 623,448; US Pat.
Mercaptotetrazoles and nitrones described in No. 266897, No. 3397987, etc.; nitrointazoles; polyvalent metal salts described in U.S. Pat. No. 2,839,405, etc.;
Thiouronium salts described in US Pat. No. 3,220,839 and the like; salts of noble metals such as palladium, platinum and gold as described in US Pat. Nos. 2,566,263 and 2,597,915 can also be used.

Furthermore, the silver halide photographic emulsion layer used in the present invention contains developing agents (such as hydroquinones, catechols,
Annobuenols, 3-pyrazolidones, ascorbic acid and its derivatives, reductones, phenylenediamines, etc.) can be contained singly or in combination of two or more.

The developing agent may be contained in the silver halogenide emulsion and/or in other suitable layers in the photographic element. The developing agent may be added dissolved in a suitable solvent or in the form of a dispersion as described in US Pat. No. 2,592,368 and French Patent No. 1,505,778.

The silver halide emulsion layer of the light-sensitive material is coated with various organic or inorganic hardeners (for example, formaldehyde, chromium alum,
1-hydroxy-3,5-dichlorotriazine soda,
glyoxal, dichloroacrolein, etc.).

The silver halide photographic emulsion layer of the light-sensitive material may also contain coating aids such as saponin, alkylaryl sulfonates as described in US Pat. No. 2,600,831, and amphoteric compounds as described in US Pat. No. 3,133,816.

The silver halide photographic emulsion of the light-sensitive material may also contain antistatic agents, plasticizers, fluorescent brighteners, development accelerators, air fog inhibitors, toning agents, color couplers, and the like. In addition, examples of anti-irradiation dyes that may be contained depending on the purpose include Japanese Patent Publication No. 41-20389, Japanese Patent Publication No. 43-350
No. 4, Special Publication No. 43-13168, U.S. Patent No. 26970
No. 37, No. 3423207, No. 2865752, British and American Patent No. 1030392, No. 1100546, etc. are used. In the present invention, a conventional gelatin-silver halide emulsion is used, but instead of gelatin, for example, albumin, agar, gum arabic, alginic acid, etc., or hydrophilic resins such as polyvinyl alcohol, polyvinylpyrrolidone, or cellulose derivatives are used. Substances that do not have a deleterious effect on the photosensitive silver halide may also be used.

The combination of dyes according to the invention may be used in combination with other sensitizing dyes. In particular, the dye represented by the general formula (1) and/or the dye represented by the general formula (), and other dyes with supersensitizing action include methine dyes (such as monomethine cyanine dyes, carbocyanine dyes and apomerocyanine dyes). ) are advantageously used. In the method of the present invention, the silver halide photosensitive material is developed after exposure to radiation.

For medical X-ray photography purposes, rapid processing is preferred in order to obtain results quickly. A developer for rapid processing requires high development activity, which means that a highly active developer or a combination thereof with a superadditive developer is used to adjust the developer to an appropriate pH (for example, pH 9-12). Obtained by making it alkaline. The developer solution also contains customary additives such as sulfites, hydroxylamine or its derivatives, hardeners, antifoggants (e.g. benzotriazole, 5-nitrobenzimidazole, 5-nitrointazole), halogen salts (e.g. bromide). potassium),
It may contain a silver halide solvent, a toning agent, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and the like. A radiation monochromatic dye image can also be obtained by a color development process as known from JP-A No. 48-55730.

On the other hand, dye (3) dye (4) known from Japanese Patent Publication No. 40-23310 (4) and dye (5) used for comparison was first methol , hydroquinone, etc., followed by processing to form a dye image.

It is also possible to use the silver image in the form of a dye image plus a silver image without bleaching the silver image during the above processing steps. Next, the present invention will be described with reference to Examples, but the present invention is of course not limited to these.

Example 1 A photographic emulsion consisting of silver iodobromide with an average grain size of 1.3 μm (AgIl. 2 mol %; gelatin (me/AgNO3 (F
f) 0.4; 0.75 mol silver salt/Kg emulsion) was prepared.

500 η/kg of emulsion as a stabilizer.
[Hydroxy-S-triazolo[1.5-a]pyrimidine was added. Sensitizing dyes were added to this silver halide emulsion as shown in Table 1. Dye (3) and Dye (4) used for comparison are imidazolooxacarbocyanine dyes having the following structures, and the Def. Pub(T9O4O
26) Corresponds to dyes A and B described in 26), respectively.

It is a merocyanine pigment.

Dye (5) The above emulsion was dyed blue (Bluetinted).
) A polyethylene terephthalate support was coated on both primed sides in such a way that a silver halide emulsion layer containing silver halide equivalent to 3.87 silver per square meter was obtained on each side.

A protective layer of gelatin was applied over each emulsion layer at a coverage of 17 per square meter. The coated material was irradiated with X-rays in the following manner. The coating was sandwiched between two sheets of terbium-activated gadolinium oxysulfide (Gd2O2S) fluorescent paper having an emission spectrum as shown in Figure 2, and an optical wedge was inserted between the film and the fluorescent paper. X-ray irradiation was performed (dose 25 milliroentgen). The exposed photographic element was processed using a roller conveyor processor according to the steps described below.

The compositions of the developer and fixer are as follows.

Developer! 0 Table 1 shows the relative sensitivity (relative value of the reciprocal of the exposure amount at a density of Capri density plus 0.5) obtained for the combinations of sensitizing dyes used and the fog density (excluding support density). Indicated.

From Table 1, it can be seen that the combination of dyes of the present invention provides high sensitivity for emission under an intensifying fluorescent screen, especially for UST9O4O2
It is clear that the sensitivity is higher than that of the combination of dyes in 6.

In addition, the comparative example of Fu7 (combination of sensitizing dye (1-5) and comparative dye-5) is the combination of sensitizing dye (1-5) and (-4) of the present application.
Compared to the combined use of , the sensitivity is only about 59%.

It can also be seen that there is a lot of fog. /168 comparative example (combination of comparative dyes -4 and (-4)) is the sensitizing dye of the present application (1
Compared to the combination of -5) and (-4), only about 62% sensitivity can be obtained. Example 2 Photographic emulsion consisting of silver iodobromide grains with an average grain size of 1.5μ (AgIl.4 mol%, gelatin (y)/AgNO
3(f) 0.5, 0.8 mol silver/I<9 emulsion) was prepared.

500 Tf9 of 5-methyl J per kg of emulsion as stabilizer
Me[hydroxy-1S-triazolo[1.5-a]pyrimidine was added. To this silver halide emulsion were added dyes as shown in Table 2. The above emulsion was applied to both primed sides of an undyed blue polyethylene terephthalate support at a rate of 3.5 silver per square meter on each side of the support.
It was coated to contain silver halide corresponding to t. A protective layer of gelatin was applied over each emulsion layer at a coating rate of 1 r/m2. For the purpose of testing safelight safety, a 5W tungsten electric lamp and a Fuji Jf. This sample was exposed for 1 minute at a distance of 1.5 m from a safelight combined with a 7 safelight filter (manufactured by Fuji Photo Film Co., Ltd.).

After developing in the same manner as in Example 1, the density on the sample was measured using a P-type density type manufactured by Fuji Photo Film. The obtained density values are shown in Table 2 as safelight fog. Further, a sample that was not exposed to light was developed in the same manner and the density was measured. The obtained density values (not including support density) are shown in Table 2 as residual colors. From Table 2, it can be seen that the photosensitive materials using the dye combination of the present invention are safe to safelight light, whereas the UST9O
It is clear that the combination of dyes No. 4,026 causes fogging under safelight light.

It can also be seen that the photographic material using the dye combination of the present invention has extremely little residual color after rapid photographic processing. In addition, comparative test black 7 using sensitizing dye (1-4) and comparative test black 8 using sensitizing dye (-4) both showed a significant increase in fog due to safelight, but the dye combination of the present invention It will be appreciated that it has transparent sensitizing properties that closely match the properties of photosensitizing screens, and is also safe against safelight light. Preferred embodiments of the invention are listed below.

However, the present invention is not limited to this. (1) In claim 1 or 2, R1 in general formula (1)
and R2 are both alkyl groups having a sulfo radical.

(To) In Claims 1 or 2, when R3 in the general formula () is an alkyl group having a sulfo radical.

(3) In the case of claim 1 or 2, the silver halide emulsion is composed of silver iodobromide grains having an average grain size of 1.0 μm to 2.0 μm.

(4) In claim 1 or 2, general formula (1
) in which both R1 and R2 are an alkyl group having a sulfo radical, and R3 in the general formula () is an alkyl group having a sulfo radical.

(5) In claim 1 or 2, the general formula '
Both R1 and R2 in (1) are an alkyl group having a sulfo radical, and R3 in the general formula () is an alkyl group having a sulfo radical, and the silver halide emulsion layer of the photographic light-sensitive material has an average grain size of approximately When it consists of silver iodochlorobromide or silver iodobromide grains of 1.0 μ to about 2.0 μ.

(6) In embodiment (5), when the silver halide emulsion layer is composed of silver iodobromide grains containing 3.0 mol or less of iodide salt.

(7) In Claim 1, the fluorescent sensitizing screen 0
- The phosphor used in the phosphor is one or more of terbium-activated gadolinium oxysulfide, terbium-activated yttrium oxysulfide, and terbium-activated lanthanum oxysulfide. When it consists of a mixture.

[Brief explanation of drawings]

FIG. 1 shows the spectral transmittance curve of a safe light filter commonly used for processing X-ray film.

Claims (1)

[Scope of Claims] 1. A photographic material comprising a support and at least one silver halide photographic emulsion layer is exposed to radiation by contacting it with a radiation intensifying screen and then subjected to photographic processing. In the method for obtaining a photographic image, the fluorescent intensifying screen has a maximum emission wavelength in the range of 500 to 570 nm and at least 1/2 of the emission energy is distributed over a wavelength of 400 nm or more, The above-mentioned halogenated photographic emulsion layer contains at least one sensitizing dye represented by the following general formula (I) and at least one sensitizing dye represented by the following general formula (II). How to get the statue. General formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In the formula, R_0 represents an alkyl group. R_1 and R_2 each represent an alkyl group, and R
At least one of _1 and R_2 is an alkyl group having a sulfo radical. m represents 1. General formula (II) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (In the formula, Z is the atomic group necessary to complete the benzoxazole nucleus; R_3 represents an alkyl group. Q is 2-thioimidazolidine-2. (Represents the atomic group necessary to complete the 4-dione nucleus.)